Cloud Native MGRS

Full(-ish) MGRS 1km grid. Data is downloaded data from https://earth-info.nga.mil/index.php?dir=coordsys&action=utm-1km-polyline-dloads (but 5 files were missing from their list). It mostly has the original columns, though attempted to combine the two length ones. Added admin boundaries following the vecorel administrative division extension, though as of now it's not vecorel compliant. Plan is to do that, and add geometry extension (and remove the similar columns from the original shapefiles).